I am moving the Solar system from our RPOD trailer to a NOBO and am expanding the system for basically double capacity.
The old system used 2 x 12v standard Marine batteries with ++500CCA each. This was connected to a 4x 100W renogy PV array with PWM 30A charger.
The (chinese) Pure Sine Wave inverter is rated at 3000W and I was able to run the AC, and microwave (not at the same time) with this setup for short periods. (both battery bank and solar limited). Short= minutes
The new system is 1060W of solar. I am upgrading to a 50A MPPT Victron charger (will retain the built-in 10A PWM charger). And I will use larger cables all around to limit voltage drop (10-12ga on each panel, 4ga at charge controller, and 1/0ga battery connectors).
Now my question, which is battery related.
I am considering buying 2x 6v 230AH batteries connected in series (true deep cycle https://www.batteriesplus.com/productdetails/sligc115) . These have no rated CCA, but are rated at 75A draw for 125 min, so I know they can at least handle that. However, being a 6V series, vs the 12v parallel system I had before, I worry about maximum current draw from the inverter.
From what I have read the PV panels themselves will be supplying large amounts of current, perhaps 40A on a sunny day (theoretical max current of panels is 48A to the 50A MPPT controller, and 9.3A to the PWM controller), and I will only run the AC on those sunny days. (the fridge will stay on propane).
So 75+40ish= 1300-1400 watts continuous. Since the AC will draw 1500w and spike higher than that, I worry about voltage drop if the 6V FLA cannot produce enough current, thus tripping the inverter, and leading to not running the AC.
I am limited by space and weight, or I would just go to 4x 6v series/parallel anyway. Lithium is way out of budget. I dont understand why people go lipo for RV when 230AH batteries can be had for $144 vs $900 for a 200AH LiFe, perhaps its the weight/space issue
I was originally going to go with 3x 12v in parallel to combat the current problem, but a group 24 12v 75AH battery costs the same as a 6v 230AH battery, of the same manufacturer (Duracell in this case). Hence my decision to go to 2x 6V in series.
Q1: would it make sense to scrap the 6v idea and just use 3x12v so that current demands are limited (1/3 current from each battery), and just cry a little at my limited storage capacity (75AH x3 aint that bad)
Q2: since the trailer is new, would using combination batteries make sense (i.e. 6v x2 in parallel with a 12v standard that came with the unit). That way the current draw would be cut in half at least.
Q3: scrap the whole idea of leaded batteries and go unleaded, and break the bank for a LiFePo4 system, and redesign everything?
Q4: find another place to put 2 more batteries and run a proper 4 x 6v system in series-parallel?
Any other thoughts?
Thank you in advance!
PS: Trial run in the Rpod trailer was successful with the 2x12v system, duty cycle should be 50% or less, so heat gen on the 3000W inverter is not that bad (I hope), and it will only be run for at most 2 hrs a day.
The old system used 2 x 12v standard Marine batteries with ++500CCA each. This was connected to a 4x 100W renogy PV array with PWM 30A charger.
The (chinese) Pure Sine Wave inverter is rated at 3000W and I was able to run the AC, and microwave (not at the same time) with this setup for short periods. (both battery bank and solar limited). Short= minutes
The new system is 1060W of solar. I am upgrading to a 50A MPPT Victron charger (will retain the built-in 10A PWM charger). And I will use larger cables all around to limit voltage drop (10-12ga on each panel, 4ga at charge controller, and 1/0ga battery connectors).
Now my question, which is battery related.
I am considering buying 2x 6v 230AH batteries connected in series (true deep cycle https://www.batteriesplus.com/productdetails/sligc115) . These have no rated CCA, but are rated at 75A draw for 125 min, so I know they can at least handle that. However, being a 6V series, vs the 12v parallel system I had before, I worry about maximum current draw from the inverter.
From what I have read the PV panels themselves will be supplying large amounts of current, perhaps 40A on a sunny day (theoretical max current of panels is 48A to the 50A MPPT controller, and 9.3A to the PWM controller), and I will only run the AC on those sunny days. (the fridge will stay on propane).
So 75+40ish= 1300-1400 watts continuous. Since the AC will draw 1500w and spike higher than that, I worry about voltage drop if the 6V FLA cannot produce enough current, thus tripping the inverter, and leading to not running the AC.
I am limited by space and weight, or I would just go to 4x 6v series/parallel anyway. Lithium is way out of budget. I dont understand why people go lipo for RV when 230AH batteries can be had for $144 vs $900 for a 200AH LiFe, perhaps its the weight/space issue
I was originally going to go with 3x 12v in parallel to combat the current problem, but a group 24 12v 75AH battery costs the same as a 6v 230AH battery, of the same manufacturer (Duracell in this case). Hence my decision to go to 2x 6V in series.
Q1: would it make sense to scrap the 6v idea and just use 3x12v so that current demands are limited (1/3 current from each battery), and just cry a little at my limited storage capacity (75AH x3 aint that bad)
Q2: since the trailer is new, would using combination batteries make sense (i.e. 6v x2 in parallel with a 12v standard that came with the unit). That way the current draw would be cut in half at least.
Q3: scrap the whole idea of leaded batteries and go unleaded, and break the bank for a LiFePo4 system, and redesign everything?
Q4: find another place to put 2 more batteries and run a proper 4 x 6v system in series-parallel?
Any other thoughts?
Thank you in advance!
PS: Trial run in the Rpod trailer was successful with the 2x12v system, duty cycle should be 50% or less, so heat gen on the 3000W inverter is not that bad (I hope), and it will only be run for at most 2 hrs a day.